Effects Of Different Forms Of Fertilizer On The Growth Of Tomato Under Partial Root-zone Irrigation

Partial root-zone irrigation(PRI) could be an efficiency water-saving irrigation without significant yield reduction. Effects of different forms of fertilizer on the growth of plants under partial root-zone irrigation receives more and more attention. In order to find a better option for the growth of tomato(Lycopersicon esculentum Mill., the effects of different ratios of organic to inorganic fertilizer-N(100% organic fertilizer-N, 70% organic fertilizer-N and 30% inorganic fertilizer-N, 70% inorganic fertilizer-N and 30% organic fertilizer-N, 100% inorganic fertilizer-N) on the yield, biomass, water use efficiency, content of chlorophyll and activity of root of tomato under partial root-zone irrigation(conventional irrigation, APRI(alternate partial root-zone irrigation) and fixed partial root-zone irrigation) were examined in a split-root experiment.In addition, the effects of nitrogen forms(ammonium-N and nitrate-N) on the photosynthesis,content of chlorophyll, biomass and water use efficiency of tomato under partial root-zone irrigation(conventional irrigation, alternate partial root-zone irrigation and fixed partial root-zone irrigation) were examined in a split-root experiment. The study was expected to provide the theoretical basis for regulating of nitrogen forms on plant growth. The results show that:70% organic and 30% inorganic fertilizer-N treatment can be used to increase significantly the content of chlorophyll and the activity of root to promote plant growth. The biomass, yield and water use efficiency of tomato under 70% organic and 30% inorganic fertilizer-N is higher than those of other ratios of organic and inorganic fertilizer-N; The content of soluble sugar and vitamin C in 70% organic and 30% inorganic fertilizer-N treatment were respectively more 16.6%, 25.8% than those in 100% inorganic fertilizer-N treatment. But organic acid and the content of nitrates decreased separately by 10.5%and 35.2% by comparing with 100% inorganic fertilizer-N treatment, thus improving the quality of tomato.Plants of the nitrate-N treatment improved the content of soluble protein, free proline and the activities of antioxidant enzymes, such as SOD, POD, CAT and APX, but decreased the accumulation amount of MDA and thus facilitated the stress resistance of tomato when compared with those of the ammonium-N treatment in an alternate irrigation cycle. The content of chlorophyll and net photosynthesis rate of tomato seedling under nitrate-N were lower compared with the ammonium-N treatment under the same irrigation method, so the biomass of ammonium-N treatment was higher than that of nitrate-N treatment.At the same forms of fertilizer, compared with other irrigation methods, the APRI treatment kept a higher net photosynthesis rate and reduced transpiration rate significantly, thus the water use efficiency could be increased remarkably. The content of soluble sugar under APRI increased by 7.3%, but the content of organic acid under APRI decreased by 16.3% comparing with conventional irrigation treatment. The activity of SOD, POD, CAT and APX and the content of soluble sugar and free proline was higher in APRI treatment than those of the conventional irrigation treatment, so APRI treatment can increase stress-tolerance of tomato.In summary, The APRI treatment had a better effect on water saving and stable yields. The optimal model of water and nitrogen supply is APRI and 70% organic and 30% inorganic fertilizer-N when organic fertilizer-N used. The APRI treatment with ammonium-N would be a better option for promoting growth and stress resistance of tomato when different forms of nitrogen were adopted.